(1) Field of the Invention
This invention relates to a saddle riding type vehicle driven by a rider straddling the vehicle, and more particularly to a mounting structure which mounts a sensor rotor for detecting wheel speed on a wheel member.
(2) Description of the Related Art
A conventional saddle riding type vehicle of this type includes a main frame, a wheel support, a sensor rotor and a wheel speed sensor (see Japanese Utility Model Publication No. H7-17609 (FIGS. 5 and 6), Japanese Unexamined Patent Publication No. 2002-79974 (FIGS. 3-5) and Japanese Unexamined Patent Publication No. 2009-255826 (FIGS. 3, 7 and 8), for example).
The sensor rotor is mounted on the front wheel, for example. The front wheel is rotatably attached to a lower portion of the wheel support which is attached to a front portion of the main frame. The sensor rotor has an annular shape, and is mounted to have an inner circumferential surface thereof located on an outer circumferential surface of a hub with an axle inserted therein. The wheel speed sensor detects outer peripheries of the sensor rotor, and outputs a signal corresponding to a rotating speed of the front wheel.
Since a wheel member on which the front wheel is mounted is generally manufactured by casting, the outer circumferential surface of the hub is rough. Therefore, in order to attach the sensor rotor on the wheel member with increased accuracy of coaxiality between the sensor rotor and the axle, the wheel member is processed to increase the accuracy of coaxially at the outer circumferential surface of the hub.
However, the conventional example with such construction has the following problems.
The conventional apparatus, which requires the outer circumferential surface of the hub of the wheel member to be processed to improve its coaxiality, has a problem of high cost due to an additional cost of the process. Since the sensor rotor is mounted on the outer circumferential surface of the hub, the sensor rotor has a large diameter. This poses a problem of an increase in the weight of the sensor rotor. Further, because of the large diameter of the sensor rotor, a stay having an increased length is required for attaching the wheel speed sensor, which poses a problem of lowered strength.